/* inflate.c -- zlib interface to inflate modules
 * Copyright (C) 1995-2002 Mark Adler
 * For conditions of distribution and use, see copyright notice in zlib.h
 */

#include "zutil.h"
#include "infblock.h"

#define  DONE INFLATE_DONE
#define  BAD INFLATE_BAD

typedef enum
{
    METHOD,     /* waiting for method byte */
    FLAG,       /* waiting for flag byte */
    DICT4,      /* four dictionary check bytes to go */
    DICT3,      /* three dictionary check bytes to go */
    DICT2,      /* two dictionary check bytes to go */
    DICT1,      /* one dictionary check byte to go */
    DICT0,      /* waiting for inflateSetDictionary */
    BLOCKS,     /* decompressing blocks */
    CHECK4,     /* four check bytes to go */
    CHECK3,     /* three check bytes to go */
    CHECK2,     /* two check bytes to go */
    CHECK1,     /* one check byte to go */
    DONE,       /* finished check, done */
    BAD
}               /* got an error--stay here */
inflate_mode;

/* inflate private state */
struct internal_state
{

    /* mode */
    inflate_mode mode;  /* current inflate mode */

    /* mode dependent information */
    union
    {
        uInt method;    /* if FLAGS, method byte */
        struct
        {
            uLong was;          /* computed check value */
            uLong need;         /* stream check value */
        } check;        /* if CHECK, check values to compare */
        uInt marker;    /* if BAD, inflateSync's marker bytes count */
    } sub;      /* submode */

    /* mode independent information */
    int nowrap;         /* flag for no wrapper */
    uInt wbits;         /* log2(window size)  (8..15, defaults to 15) */
    inflate_blocks_statef
    * blocks;            /* current inflate_blocks state */

};


ZEXPORT(int) inflateReset( /* z) */
    z_streamp z)
{
    if (z == Z_NULL || z->state == Z_NULL)
        return Z_STREAM_ERROR;
    z->total_in = z->total_out = 0;
    z->msg = Z_NULL;
    z->state->mode = z->state->nowrap ? BLOCKS : METHOD;
    inflate_blocks_reset(z->state->blocks, z, Z_NULL);
    Tracev((stderr, "inflate: reset\n"));
    return Z_OK;
}


ZEXPORT(int) inflateEnd( /* z) */
    z_streamp z)
{
    if (z == Z_NULL || z->state == Z_NULL || z->zfree == Z_NULL)
        return Z_STREAM_ERROR;
    if (z->state->blocks != Z_NULL)
        inflate_blocks_free(z->state->blocks, z);
    ZFREE(z, z->state);
    z->state = Z_NULL;
    Tracev((stderr, "inflate: end\n"));
    return Z_OK;
}


ZEXPORT(int) inflateInit2_( /* z, w, version, stream_size) */
    z_streamp z,
    int w,
    const char* version,
    int stream_size)
{
    if (version == Z_NULL || version[0] != ZLIB_VERSION[0] ||
        stream_size != sizeof(z_stream))
        return Z_VERSION_ERROR;

    /* initialize state */
    if (z == Z_NULL)
        return Z_STREAM_ERROR;
    z->msg = Z_NULL;
    if (z->zalloc == Z_NULL)
    {
        z->zalloc = zcalloc;
        z->opaque = (voidpf)0;
    }
    if (z->zfree == Z_NULL) z->zfree = zcfree;
    if ((z->state = (struct internal_state FAR*)
                    ZALLOC(z, 1, sizeof(struct internal_state))) == Z_NULL)
        return Z_MEM_ERROR;
    z->state->blocks = Z_NULL;

    /* handle undocumented nowrap option (no zlib header or check) */
    z->state->nowrap = 0;
    if (w < 0)
    {
        w = -w;
        z->state->nowrap = 1;
    }

    /* set window size */
    if (w < 8 || w > 15)
    {
        inflateEnd(z);
        return Z_STREAM_ERROR;
    }
    z->state->wbits = (uInt)w;

    /* create inflate_blocks state */
    if ((z->state->blocks =
             inflate_blocks_new(z, z->state->nowrap ? Z_NULL : adler32, (uInt)1 << w))
        == Z_NULL)
    {
        inflateEnd(z);
        return Z_MEM_ERROR;
    }
    Tracev((stderr, "inflate: allocated\n"));

    /* reset state */
    inflateReset(z);
    return Z_OK;
}



#undef  NEEDBYTE
#define NEEDBYTE { if (z->avail_in == 0) return r;r = f; }

#undef  NEXTBYTE
#define NEXTBYTE (z->avail_in--, z->total_in++, *z->next_in++)


ZEXPORT(int) inflate( /* z, f) */
    z_streamp z,
    int f)
{
    int r;
    uInt b;

    if (z == Z_NULL || z->state == Z_NULL || z->next_in == Z_NULL)
        return Z_STREAM_ERROR;
    f = f == Z_FINISH ? Z_BUF_ERROR : Z_OK;
    r = Z_BUF_ERROR;
    while (1) switch (z->state->mode)
        {
            case METHOD:
                NEEDBYTE
                if (((z->state->sub.method = NEXTBYTE) & 0xf) != Z_DEFLATED)
                {
                    z->state->mode = BAD;
                    z->msg = (char*)"unknown compression method";
                    z->state->sub.marker = 5; /* can't try inflateSync */
                    break;
                }
                if ((z->state->sub.method >> 4) + 8 > z->state->wbits)
                {
                    z->state->mode = BAD;
                    z->msg = (char*)"invalid window size";
                    z->state->sub.marker = 5; /* can't try inflateSync */
                    break;
                }
                z->state->mode = FLAG;
            case FLAG:
                NEEDBYTE
                b = NEXTBYTE;
                if (((z->state->sub.method << 8) + b) % 31)
                {
                    z->state->mode = BAD;
                    z->msg = (char*)"incorrect header check";
                    z->state->sub.marker = 5; /* can't try inflateSync */
                    break;
                }
                Tracev((stderr, "inflate: zlib header ok\n"));
                if (!(b & PRESET_DICT))
                {
                    z->state->mode = BLOCKS;
                    break;
                }
                z->state->mode = DICT4;
            case DICT4:
                NEEDBYTE
                z->state->sub.check.need = (uLong)NEXTBYTE << 24;
                z->state->mode = DICT3;
            case DICT3:
                NEEDBYTE
                z->state->sub.check.need += (uLong)NEXTBYTE << 16;
                z->state->mode = DICT2;
            case DICT2:
                NEEDBYTE
                z->state->sub.check.need += (uLong)NEXTBYTE << 8;
                z->state->mode = DICT1;
            case DICT1:
                NEEDBYTE
                z->state->sub.check.need += (uLong)NEXTBYTE;
                z->adler = z->state->sub.check.need;
                z->state->mode = DICT0;
                return Z_NEED_DICT;
            case DICT0:
                z->state->mode = BAD;
                z->msg = (char*)"need dictionary";
                z->state->sub.marker = 0; /* can try inflateSync */
                return Z_STREAM_ERROR;
            case BLOCKS:
                r = inflate_blocks(z->state->blocks, z, r);
                if (r == Z_DATA_ERROR)
                {
                    z->state->mode = BAD;
                    z->state->sub.marker = 0; /* can try inflateSync */
                    break;
                }
                if (r == Z_OK)
                    r = f;
                if (r != Z_STREAM_END)
                    return r;
                r = f;
                inflate_blocks_reset(z->state->blocks, z, &z->state->sub.check.was);
                if (z->state->nowrap)
                {
                    z->state->mode = DONE;
                    break;
                }
                z->state->mode = CHECK4;
            case CHECK4:
                NEEDBYTE
                z->state->sub.check.need = (uLong)NEXTBYTE << 24;
                z->state->mode = CHECK3;
            case CHECK3:
                NEEDBYTE
                z->state->sub.check.need += (uLong)NEXTBYTE << 16;
                z->state->mode = CHECK2;
            case CHECK2:
                NEEDBYTE
                z->state->sub.check.need += (uLong)NEXTBYTE << 8;
                z->state->mode = CHECK1;
            case CHECK1:
                NEEDBYTE
                z->state->sub.check.need += (uLong)NEXTBYTE;

                if (z->state->sub.check.was != z->state->sub.check.need)
                {
                    z->state->mode = BAD;
                    z->msg = (char*)"incorrect data check";
                    z->state->sub.marker = 5; /* can't try inflateSync */
                    break;
                }
                Tracev((stderr, "inflate: zlib check ok\n"));
                z->state->mode = DONE;
            case DONE:
                return Z_STREAM_END;
            case BAD:
                return Z_DATA_ERROR;
            default:
                return Z_STREAM_ERROR;
        }
    #ifdef NEED_DUMMY_RETURN
    return Z_STREAM_ERROR; /* Some dumb compilers complain without this */
    #endif
}